Chemical compounds and their use as rust and corrosion inhibitors



United States Patent 3,183,069 CHEMICAL COlVIPOUNDS AND THEIR USE AS RUST AND CORROSION INHIBITORS John H. Udelhofen, Calumet City, 11]., assignor to Standard Oil Company, Chicago, 11]., a corporation of Indiana No Drawing. Filed Apr. 28, 1961, Ser. No. 106,197 3 Claims. (Cl. 44-71) This invention relates to chemical compounds and their use as rust inhibitors and corrosion inhibitors n normally liquid oleaginous compositions. This inventlon further relates to and provides normally liquid oleaginous compositions, especially in the presence of water, inhibited against rust and corrosion by the inclusion therm of certain N-substituted amic acid (monoamides) compounds provided herein.

In the handling and storage of many normally l1qu1d hydrocarbons and hydrocarbon products, serious problems of corrosion are encountered particularly corrosion to ferrous metal parts. Under conditions of handling the storage of normally liquid hydrocarbons, water often becomes included with the hydrocarbon through seepage, condensation or even from processing of the hydrocarbon. Also present in the hydrocarbon in many instances are acidic and/or caustic substances in small amounts resulting from prior treatment of the hydrocarbons, e.g. from acid treating and/ or caustic treating of fuel Oil S and lubrieating oils. Such acidic and/ or caustic materials are corrosive toward metal parts such as storage tank walls, valves, pipelines, tank car walls, burners, gasoline tanks, crankcases, etc. Other corrosive substances may be formed through oxidative deterioration of the hydrocarbon in the presence of oxygen particularly if the hydrocarbon is stored for substantial periods of time or stored or supported under adversely high temperature conditions. The water present in the hydrocarbon often causes the formation of two separate phases, i.e. a hydrocarbon phase and an aqueous phase. The corrosive materials become distributed throughout both the hydrocarbon and aqueous phases and it becomes desirable, if not necessary, to protect against corrosion of metal parts from both phases. The presence of the water phase also, of course, promotes rusting of metal parts such as tank walls, pipes, etc. The present invention provides normally liquid hydrocarbon compositions which have imparted thereto the ability to protect against rust and corrosion of both .phases by the inclusion therein of certain corrosion inhibiting agents.

The compounds of this inventlon correspond to the structural formula:

wherein R is an open-chain (non-cyclic) aliphatic hydrocarbon group containing from 8 to 22 carbon atoms and A corresponds to the empirical formula: -C H,(O),, wherein x is 1 to 2 inclusive. R may be saturated, monounsaturated, di-unsaturated or poly-unsaturated, preferably saturated, mono-unsaturated or di-unsaturated.

In the preferred embodiments, R contains from 12 to 18 carbon atoms and each carbon atom of A is linked directly to a different group of the above formula.

The compounds are monoamides of certain dioic acids and will be referred to herein as N-aliphatic dlioamic acids (wherein the aliphatic group is R as defined above) in view of the existence of one non-reacted carboxylic acid group in addition to the amide linkage, although the nomenclature N-aliphatic dioic acid-monoamide may also be used.

The N-aliphatic dioamic acids may be used in accordance herewith in a normally liquid hydrocarbon in amounts sufficient to inhibit corrosion and more desirably in amounts sufiicient to inhibit corrosion caused by the presence of water in a separate phase in contact with the normally liquid hydrocarbon. More advantageously, the corrosion inhibitors may be used in amounts of from about 0.00005 to about 10 weight percent in a normally liquid hydrocarbon and preferably in amounts of about 0.0001 to about .01 weight percent. The salts, e.g. the amine salts and especially the substituted-imidazolinium salts, of the N-aliphatic dioamic acids can also be prepared for use as effective corrosion inhibitors by reacting the N- aliphatic dioamic acid with a substituted imidazoline.

The R group of the compounds apparently serves two functions. The hydrocarbon chain provides the property of oil-solubility and also provides a sufficiently thick mononuclear layer for the purpose of protecting metal surfaces against rust and corrosion.

The compounds useable in accordance herewith include, for example, the monoamides of malic acid, 2,2-dihydroxybutanedioic acid, tartaric acid, methoxypropanedioic acid, diglycolic acid, the oxy, hydroxy, and dihydroxy Z-methylpropane-1,3-dioic acids, etc. More specific examples of useable monoamides are N-tallow'tartaramic acid, N- lauryl 2,2-dihydroxy-butanedioamic acid, N-lauryl digylcolamic acid, N-docosyl 2-methylpropane-1,3-dioamic acid, N-eicosyl tartaramic acid, N-palmityl malamic acid, N-tallow diglycolamic acid, N-oleyl malamic acid, N-octyl 2,2-dihydroxy-butanedioamic acid, N-octyl tartaramic acid, N-myristyl diglycolamic acid, N-octenyl tartaramic acid, N-coco 2,Z-dihydroxy-butanedioamic acid, N-tallow malamic acid, N-soybean methoxy-propanedioamic acid, N-coco diglycolamic acid, N-stearyl tartaramic acid, N- linoleyl malamic acid, N-linolenyl methoxypropanedioamic acid, N-linolenyl tartaramic acid, N-dodecdienyl malamic acid, N-palmityl 2,2-dihydroxy-butanedioamic acid, N-lauryl malamic acid, N-decyl diglycolamic acid, and the like. The designations coco, s-oybean" and tallow are used to designate aliphatic groups derived from coco amines, soybean amines and tallow amines respectively. The coco, soybean and tallow amines are derived from coconut fatty acids, soybean fatty acids and tallow fatty acids by reaction of the fatty acids with ammonia resulting in the formation of mixtures of amines having varying molecular weights. The amines prepared from the fatty acids are available commercially under the tradename Armeen. The Armeens may advantageously be used as a source of primary aliphatic amines in preparing the dioamic acids of this invention. Examples of the Armeens are Armeen T (derived from tallow fatty acids and containing about 2% tetradecyl amine, 24% hexadecyl amine, 28% octadecyl amine and 46% octadecenyl amine) and Armeen 12 (containing 2% decyl amine, dodecyl amine and 3% tetradlecyl amine). Other amines from which the dioamic acids may be derived are the Alamines as Alamine 26 (a mixture of saturated, mono-unsaturated and di-unsaturated C primary amines) and Alamine 21D (distilled primary coco amine).

The N-aliphatic dioamic acids of this invention may be conveniently prepared by reacting equimolar amounts of the corresponding aliphatic amine the corresponding dioic acid. The reaction may be conveniently carried out at temperatures in the range of 100-200 C. or higher if desired. The reaction proceeds at a more rapid rate at higher temperatures and at a slower rate at lower temperatures. The reaction is terminated, e.g. by removal of heat, after formation of one mole of water per mole of dioic acid or aliphatic amine. Care should be taken not to permit the reaction to be carried out until two moles of water are split out per mole of amine or dioic acid because the amide linkage may thereby be converted to the imide. Because the reaction is more difficult to control at 'higher temperatures, it is preferred that the reaction be carried out at a lower temperature, e.g. within the range of 100-150 C. where the reaction rate is slower and where the reaction may be more conveniently controlled without much loss of the amide to formation of imides; The dioic acids may be used in the hydrous form, e.g. as the monohydrate, if desired. In such cases, the water of the hydrate should be taken into account in determining the amount of water from the reaction in view of the amount of water recovered.

The reactions in forming the dioamic acids useful in this invention may conveniently be carried out using a solvent in the reaction medium. Useable solvents are the aromatic hydrocarbons and particularly the lower boiling hydrocarbons such as benzene, toluene, xylene, ethylbenzene and the like. It is usually not particularly desirable to remove the solvent after the reaction, especially where the solvent is an aromatic hydrocarbon which may be permitted to be incorporated into the normally liquid hydrocarbon to which the dioamic acids are added. These solvent containing compositions may be from to 75 weight percent of the dioamic acid and may be utilized as a concentrate. The lower boiling aromatic hydrocarbons are preferred because they boil within the most desirable reaction temperature ranges. The solvents may function in controlling reaction temperature in that the reaction may be carried out at the reflux temperature of the solvent.

As a typical preparation of an N-aliphatic dioamic acid, nine grams of tallow amine dissolved in 100 ml. of xylene were added slowly to 4.02 grams of diglycolic acid in 100 ml. of boiling xylene. The reaction vessel was equipped with a Dean-Stark trap to collect azeotropic water formed as a result of the reaction. After two hours, 0.60 ml. water was recovered. The solvent was removed by vacuum distillation leaving twelve grams of N-tallow diglycolamic acid as a semi-solid residue.

The normally liquid hydrocarbons include those hydrocarbons boiling in the gasoline through lubricating oil range and preferably those normally liquid hydrocarbons boiling in the gasoline distillation range. Examples of normally liquid hydrocarbons are gasoline, heater oil, jet fuel, kerosene, mineral lubricating oils, synthetic hydrocarbon lubricating oils, furnace oils, residual heating oils, fuel oil blends containing residual and distillate fuel oils, e.g. Bunker C, gas oils and other residual and distillate fuel oils. The normally liquid hydrocarbons may contain other non-hydrocarbon components, e.g. sulfur, normally present in diesel fuels. The lubricating oils may be sulfur extracted if desired. The normally liquid hydrocarbons may be virgin hydrocarbons or may be processed, e.g. by cracking, alkylation, reforming, isomerization and the like. The rust inhibitors of this invention are believed to be especially effective in petroleum hydrocarbons and their preferred use is in combination with normally liquid hydrocarbons boiling in the gasoline distillation range.

In order to illustrate the rust and corrosion inhibition properties of the compositions of this invention, examples of compositions of this invention were prepared and subjected to rust and corrosion test as follows:

Indiana Conductometric Ru'st Test (static).This test tests for corrosion inhibition and rust inhibition properties in the presence of corrosive acidic and caustic substances. The test was run using gasoline as the hydrocarbon phase. In accordance with the procedure of the test, the samples identified in the left-hand column of the table were each placed with an equal volume of water containing added caustic and/or acidic substances in a test tube and stirred briefly to permit the addition agent to become distributed within both the hydrocarbon and aqueous phases. An S-shaped steel test strip, having an electrical terminal at each end of the S is then immersed in the hydrocarbon phase to reach adsorption equilibrium and the electrical resistance is noted as a control resistance value. The steel test strip is then lowered into the aqueous phase and after 24 hours the change in electrical resistance is taken as a measure of rusting and corrosion in both the aqueous and hydrocarbon phases during the 24- hour period. A determination of rusting and corrosion inhibition was made in terms of corrosion rate measured in mils penetration per day times 10 The mils penetration per day were converted to percent reduction in corrosion by the following equation:

1' -r I =percent reduction in corrosion r =corrosion rate of steel strip in fuel with inhibitor. r =corrosion rate of steel strip in fuel with no inhibitor.

Table Rust and Corrosion Inhibition, Percent Reduction in Corrosion Hydrocarbon Phase Gasoline Gasoline Gasoline Gasoline Gasoline Gasoline Gasoline Aqueous Phase Deionized 0.1% M10] 0.1% HaGi Water 3.6)(10-"75 10- MHCl 3.6Xl0 0.1% NaCl +3.6X +10 Alone 1101 NaOH 10 NNaOI-I NaOH 0.0006% N-tallow diglycolemic acid in Hydrocarbon Plies 98 98 97 98 0.00037% N-tallow malamic Hydrocarbon Phase 96.3 0.000723% N-tallow maiamie acid in Hydrocarbon Phase 100 97. 4 98. 2 95. 5 S9. 2 0.00037% 1 N-tallow tartaramic acid 4 in Hydrocarbon Phase 97. 2 0.00073% 3 N-tallow tartaramie acid 4 in Hydrocarbon Phase 100 98. 4 97. 5 94. 5 97. 3

1 One pound per thousand barrels.

F Preparation: 12 g. tallow amine dissolved in 100 ml. toluene were added slowly to 5.20 g. of malic acid dissolved in 100 ml. boiling toluene. The reaction vessel was equipped with a distillation trap to collect azeotropic water formed in the reaction. When 0.75 mi. of water was obtained, the reaction was stopped and the solvent was removed in vacuo ieaving 16 g. product.

I Two pounds per thousand barrels.

4 Preparation: Same as (i) above except that equimolar amounts of tallow amine and tartaric acid were reacted under the conditions given.

The data of the table indicate the ability of the compositions of this invention to inhibit rust and corrosion even in concentrations lower than .0004 weight percent. In comparison with the control (containing no additive) the compositions of this invention demonstrated an excellent ability in inhibiting rust and corrosion in both the aqueous and hydrocarbon phases in the presence of water and under caustic and acidic conditions.

It is evident from the foregoing that I have provided compounds useful in normally liquid hydrocarbon oils for the prevention of rust and/ or corrosion.

I claim:

1. A gasoline composition which comprises a major amount of a normally liquid hydrocarbon fuel boiling in the gasoline distillation range and a minor amount, sufficient to inhibit corrosion, of N-tallow diglycolamic acid.

2. The composition of claim 1 wherein said minor amount is in the range of from about 0.0001 to about 0.1 weight percent.

3. An addition agent concentrate comprising from 10 to by weight of N-tallow diglycolamic acid and from about to 25% by weight of a hydrocarbon solvent, said concentrate being capable of dilution with a normally liquid hydrocarbon to inhibit corrosion of said liquid hydrocarbon.

References Cited by the Examiner UNITED STATES PATENTS DANIEL E. WYMAN, Primary Examiner.

JULIUS GREENWALD, Examiner. 

1. A GASOLINE COMPOSITION WHICH COMPRISES A MAJOR AMOUNT OF A NORMALLY LIQUID HYDROCARBON FUEL BOILING IN THE GASOLINE DISTILLATION RANGE AND A MINOR AMOUNT, SUFFICIENT TO INHIBIT CORROSION, OF N-TALLOW DIGLYCOLAMIC ACID. 